How to adjust a mountain bike rear derailleur?

Are your rear gears unstable, or have you just installed your new derailleur? It's time to adjust it! Here's a video to help you perform this tricky operation on your mountain bike.

Time : 20 min
Level : Medium
Tools : Allen key set | Flat-nose pliers | Phillips screwdriver

Steps

Position chain on smallest sprocket, then release derailleur cable.
Adjust the low stop (High) so that the alignment a between the derailleur pulley and the outer surface of the smallest sprocket.
Operate the derailleur by hand to set the derailleur's low stop in line with the largest sprocket.
Screw the tensioning knob on the shifter all the way in, then unscrew it by 2 turns.
Replace the derailleur cable in the housing, tensioning it slightly with the flat pliers.
Place the transmission on the smallest chainring and the largest sprocket.
Set the gearscrew to the distance between sprocket and derailleur pulley recommended by the manufacturer (usually 5 or 6 mm).
Scan all gears to ensure smooth shifting.
Finalize the adjustment with the tensioning wheel on the gearshift until you obtain the best possible shifting smoothness.
Probikeshop tip: to facilitate final adjustment, lubricate your mountain bike transmission.